First, let me get this disclaimer out of the way: I am not a cosmetologist, I color and bleach my hair myself, and these are the things that have worked for me. I have yet to experience any damage or breakage from bleach.
Okay, so two methods come to mind in terms of bleach and retaining your curl pattern. The first is to use low volume developer and ammonia free bleach. This is what I do to bleach my hair. I have off black hair that is about a level 1 and if I had to type my hair, Iíd say I was a type 4. I use ionís sensitive scalp 20 volume developer and ion color brilliance ammonia free lightener. Itís powder bleach that uses potassium persulfate instead of ammonia as a bleaching agent. Now, itís debatable whether potassium persulfate is preferable to ammonia persulfate, but that is another conversation. Iíve never used an ammonia based powder, so I just stick to what has been working for me. You can buy both of these products at sallyís. I only use a 20 volume developer because it is unnecessary to use developers with higher concentrations of peroxide. You are more likely to damage your hair if you use a 30 or 40 vol. not because they are stronger, but because they lift at a faster rate. Even with my natural level 1 black hair, I can get to a dark blonde color in one session. Iíve been thinking about trying a 10 volume next time because that would be even better for my hair.
The next option is to use the Clairol mix tones clear with their 20 vol. clairoxide developer. Clairol suggests using this as a replacement for their old luminize product. Iíve never used it, but it has good reviews on sallyís website. I might try it in the future. The advantage to using this instead of the previous method is that lightens the hair without any bleach at all. Here are two links that explain the process in detail:
How I achieve my color - CurlyNikki Forums
Discontinued Products & Recommendations from Clairol Professional
(scroll down to the 4th product)
No matter how you lighten your hair, it is important to maintain its health by incorporating more protein into your regimen. I use a light protein conditioner whenever I feel like I need it, and I use the aphogee two-step treatment every 6 to 8 weeks. I have yet to experience any change in my curl pattern.
So, thatís it! Sorry for the long post, I just wanted to make sure I explained everything in detail.